ISHS Acta Horticulturae 463: VIII International Symposium on Plant Bioregulation in Fruit Production
IS AUXIN EXPORT OF APPLE FRUIT AN ALTERNATIVE SIGNAL FOR INHIBITION OF FLOWER BUD INDUCTION ? |
| Authors: | R. Callejas, F. Bangerth |
| Keywords: | Auxin transport, gibberellins, Malus domestica, flower induction |
| Abstract:
The basipetal transport of IAA could play an important role in the process of flower induction in apple trees. In an effort to try to verify this hypothesis, experiments with biennial-bearing ‘Elstar’ and non-biennial-bearing ‘Golden Delicious’ apple trees were done. The trees were sprayed 35 ‘days after full bloom’ (dafb) with GA3, GA4 and GA7 at a concentration of 250 mg-1-1. Fruit and shoot tip exudate samples were taken at regular intervals after flowering for analysis of IAA-contents via Radioimmunoassay After full bloom it was possible to measure a significant amount of diffusible IAA collected from fruits and shoots of apple, which increased during the critical phase of the ‘flower induction’ (FI) (4–6 weeks after full bloom). The sprayings of GA3, GA4 and GA7 caused an increase in diffusible IAA. There was a clear influence of the seed number on the amount of diffusible IAA from fruits. Vegetative growth was increased by all GA sprayings. The increased transport of IAA during the critical phase of FI, specially after the application of gibberellins, supports the hypothesis that IAA export out of fruits and shoot tips is involved in FI. However, there are no significant differences between the two apple cultivars or within the different gibberellins applied. | |
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